Compost plant draws excitement, skepticism

An ambitious and divisive proposal to build a waste-to-energy plant in Byxbee Park won cautious praise from Palo Alto's utility commissioners Wednesday night.

The Utilities Advisory Commission discussed the preliminary results from a study that looked at the potential costs of building an anaerobic digestion facility — a plant that would convert local food scraps, yard trimmings and sewage sludge into electricity. Commissioners didn't endorse the project, citing a host of unanswered questions about its costs, but they agreed that a local anaerobic digestion facility would bring a host of environmental benefits to Palo Alto.

Chief among these benefits is retiring the incinerators that currently burn Palo Alto's sewage sludge, Vice Chair Jon Foster said. He echoed several public speakers who characterized this practice as an embarrassment for a city that takes such pride in its green accomplishments.

"For us to be burning our biosolids is terrible," Foster said. "It's expensive and the contributions to the environment couldn't possibly be worse.

"We should send a message to the City Council that we should absolutely move forward in the direction that would lead to the closure of the incinerator," Foster said.

Commissioners briefly discussed the facility's energy potential and agreed that while the project holds great promise, it's too early to have a serious discussion about whether the city should pursue it. Palo Alto's consultant, Alternative Resources, Inc., released the preliminary feasibility study last month and is scheduled to complete the final study in September.

Early numbers show that processing Palo Alto's yard trimmings, food waste and sewage sludge in a local anaerobic digestion facility would cost the city more than $100 per ton, while shipping yard trimmings to Gilroy and food waste to San Jose would cost about $70 per ton.

Former Mayor Peter Drekmeier, a leading proponent of building a local plant, said the numbers are skewed because they don't consider the fact that without a new facility, the city would have to retrofit its existing incinerators or build a new one — a project that he said would cost tens of millions of dollars.

Drekmeier is leading a drive to "undedicate" a roughly 9-acre portion of parkland at the site of the existing landfill. The landfill is scheduled to close next year, at which time the land is slated to revert to parkland.

Drekmeier's coalition, the Palo Alto Green Energy and Compost Initiative, has already collected enough signatures to place the issue on the November ballot.

Other residents, including former Councilwoman Emily Renzel and former Vice Mayor Enid Pearson, oppose the use of parkland for an industrial waste operation. Renzel pointed out at Wednesday night's meeting that the city is already conducting a separate master plan for the Regional Water Quality Control Plant — a plan that would consider Palo Alto's options for processing sewage.

"I think you need to understand that the biggest energy and greenhouse-gas savings can occur by just dealing with the water-quality plant," Renzel told the commission. "You do not need to take parkland and build a power plant there."

The commission stayed away from the thorny land-use issue and focused on the plant's capacity to supply gas and electricity. The facility's generator would produce between 1.5 and 2 megawatts — enough to supply between 1.2 and 1.5 percent of the city's annual electricity usage, according to a report from Jon Abendschein, a resource planner at the Utilities Department. It would also nudge the city toward its goal of getting 33 percent of its electricity from renewable sources by 2015, the report stated.

Foster called the energy-generation component of the project "fabulous" and the "holy grail" of locally generated renewable energy. His colleagues agreed, though they also acknowledged that this green project would also have to make financial sense to get their endorsement. Commissioner Steve Eglash said there are "a lot of wonderful reasons for doing this," but also warned against entering a situation in which the utility would pay "exorbitantly high rates" to subsidize the project.

Posted by Maureen Reilly, a resident of another community
on Mar 3, 2011 at 6:35 am

Stories like these are confusing.

The city is discussing a sludge digester that would take sewage sludge and food waste. The digestion gases would be collected for fuel to turn a turbine for energy.

Then they say they could then close down the incinerator.
Really? Then what will happen with the digested sludge?

First: most cities use the digestion gases from their sludge digesters for energy already. Most use the uncleaned gases, but it is possible for the larger plants to clean the digester gas for sale as natural gas. Small facilities are still flaring off the digester gases.

Second: After the digestion process, there is still a great quantity of sludge.

If Palo Alto builds the digesters, what do they propose to do with the sludge that the digesters generate? They need to build sludge management costs into their reckoning on the digester plan.

It looks like there are plans to turn the sewage sludge to compost.
Where will that happen? At what cost?
Do people want to eat food grown in Palo Alto sludge?

Not likely.

Or will the City still need the sludge incinerator? Are they going to spend all that digester money and still need to incinerate the remains?

Munich Germany uses both a modern sludge digester gas collection system and then a fluidized bed incinerator to manage the remaining sludge. They generate enough energy to meet all the energy needs of the plant....which runs entirely on the energy the sludge produces.

Sludge Watch

Posted by Helane Shields, a resident of another community
on Mar 3, 2011 at 10:14 am

Most sewage treatment plants give Class A sewage sludge "biosolids" compost away for free. There is little or no market for Class A sludge biosolids because it is subject to explosive pathogen regrowth (primarily fecal coliform and salmonellae), and all sludge contains a great deal of toxic industrial wastes.

Pretreatment programs are not being enforced because of the fear that the expense of requiring companies to properly treat, recycle and/or dispose of their hazardous wastes could cost local jobs. Even the US EPA is looking the other way to protect US jobs, as industrial chemicals are dumped in public sewers. The wastewater treatment process reconcentrates the pollutants in the sludge biosolids- both Class B AND Class A.

For more information on people sickened from exposure to Class A sludge biosolids compost: Web Link

University of Wisconsin scientists whose research is funded by US EPA, have recently warned the EPA and waste industry of a new risk with land application of both Class B and Class A sewage sludge - infectious prions from human and animal sources. Prions cause Mad Cow Disease, Chronic Wasting Disease, Scrapie, and in humans, Creutzfeldt Jakob Disease. Wastewater treatment does NOT inactivate prions, but reconcentrates them in the sludge. See Web Link for more information.

Europe is way ahead of USA in using sludge as a renewable resource to produce biogas, heat, energy, power, etc. New non-polluting technologies protect agricultural land, save money, and reduce both greenhouse gases and the need to import costly foreign oil and gas.

No, residents would not be growing their veggies in sewage sludge....as these biosolids would be in a separate composting track as the yard and food waste.

Kudos to the City Council and to Vice Chair Foster.

Posted by registered user, Cedric de La Beaujardiere, a resident of Barron Park
on Mar 3, 2011 at 6:28 pm

The economic feasibility study actually indicates that through PUBLIC-financing of a local Dry Anaerobic Digestion facility (Dry AD), the city and rate-payers would save $4 million over a 20-year period, compared to the city's default plan, and save $8 million compared to sending our food-waste to a regional Dry AD plant. Further, if the city won a 30% grant, we would save $19 to $23 million over the same period, or the equivalent of about $1 million per year. Where the article says, "local anaerobic digestion facility would cost the city more than $100 per ton", this is for the case of PRIVATE-financing of the facility. And, since I keep getting this question, yes, the public financing figures do include the cost of debt financing.

@Maureen:
To clarify some of your questions/statements:
1) The proposed Anaerobic Digester would generate methane, which would then either be burned for electricity (at the total prices listed above), or the biogas could be cleaned to produce Natural Gas (for our pipelines), and/or Compressed Natural Gas (a vehicle fuel).
2) The city's current incinerator does not capture waste heat for energy, because it is an old-fashioned type. It would have no role in the conversion of methane to electric energy, nor in the digestate disposal. We currently spend energy and money to incinerate our sewage, whereas AD would enable us to earn energy and money from our sewage.
3) The digestate would be composted with yard trimmings to make compost at the 10-acre site. The cost/savings of composting instead of landfilling the digestate is included in the financial study.
4) Actually, one of the alternatives is handling the sewage-only through Wet AD, and the study includes the cost of hauling that digestate to a landfill. We have asked that the consultants consider the feasibility of doing Wet AD for food and sewage, and composting the digestate with yard trimmings.
5) The original intention was to have sewage and food processed in separate, parallel streams, so that the compost from the sewage would be used for lanscaping type applications, and that from food would be suitable for gardens. However, this may increase the cost, while combining them, at least in Wet AD systems, has been shown to increase the energy produced beyond what you would expect from digesting them separately and summing their energy. The value of this increased energy is likely greater than the decrease in value of the compost product.

@Helane
6) Palo Alto does not have heavy industries anymore, and analysis of our sewage shows at most low concentrations of heavy metals. I'll try to send a link to that report if I have the time and can find it later.
7) We need to do something with our sewage, so we might as well get energy out of it before we get rid of it. AD and composting both reduce its mass, and both kill pathogens (I can't recall to what percent, but the consultants could probably tell you at the next public meeting). It seems to me (from skimming wikipedia) that "Class A" is a pretty broad category, just referring to treating the sewage against pathogens, but not grading by efficacity of said treatment.

The next public meeting will be on Wednesday March 9th, 7-9pm Art Center Auditorium, ad will mostly cover the GHG analysis and whatever was left to cover on the economic analysis when they ran out of time.

Posted by Annette Isaacson, a resident of Midtown
on Mar 3, 2011 at 9:14 pm

It's important to remember that shipping our food waste and yard clippings to Gilroy may cost $70. a ton today when gasoline is under $4.00 a gallon. How much will it cost when gasoline is $5.00 or $10.00 a gallon? The feasibility study hasn't given us figures that take into consideration an almost certain increase in the cost of gas for transporting our waste to another community so comparing this cost to the cost of a Wet or Dry Anaerobic Digester isn't quite fair. Let's handle our wastes locally.

Posted by More Palo Alto Nonsense !!!!, a resident of College Terrace
on Mar 4, 2011 at 2:56 pm

Reading all this - does it make you feel Palo Altans are out of touch with reality. Maybe its is a handful of people like this.

Such bogus ideas need to be dumped first. Get a real job folks.

Posted by Bryan Long, a resident of Crescent Park
on Mar 6, 2011 at 1:44 pm

@ Maureen, yes, these stories are often confusing, but the stories and the discussions are also how we reduce our confusions. Maybe I can help clear up a few of the questions.

Palo Alto's incinerator seemed like a good idea at the time, as a way to reduce the high volume of sludge down to a small quantity of ash. But that was back when natural gas was really cheap and most of us had never heard of greenhouse gasses or climate change. Since that era, most municipalities throughout the US have moved away from incineration, and now do open-air composting of the sludge and then give it away for use as a soil amendment or as fill for land reclamation. According to the EPA, about half of US sewage sludge is used on agricultural land. So like it or not, most of us are eating food grown in soil amended with sewage sludge. I share concerns about contaminates in the sludge used on farmland, particularly sludge from industrial areas. As Cedric notes, our sewage sludge is pretty clean relative to other urban areas, but even so.

Anaerobic (no oxygen) digestion of sewage sludge is now very popular across the U.S. as a step after de-watering and before open air (aerobic) composting. The digestion process retrieves some of the energy content of the sludge, and reduces the volume by about 50%. An additional benefit is that the majority of pathogens are destroyed by the high heat and biological activity of anaerobic digestion. Heavy metals are not affected by digestion, of course, and if they were a problem in the undigested sludge, they will be a more concentrated problem in the digested sludge. But metal concentrations can be measured, and various remedial methods are available to remove some of these prior to dewatering of the sludge. My understanding is that the metals concentration at the PA facility would not exceed normal soil levels after digestion, but I'm not an authority on that.

So digestion of sewage sludge is not a panacea, but it is a good component in an overall system of waste handling. The digested sludge, 50% or more reduced in volume, would require a second-stage aerobic composting. We could either do that on our land, or transport the sludge elsewhere for composting. Which we should do depends on financial, environmental and aesthetic trade-offs, which are still under debate. The composted digestate should be tested for pathogens, metals and other compounds, and I would prefer it was used only in commercial landscaping or land reclamation, but if it passes EPA standard it could also be given away for commercial agricultural use.

Adding food waste to the sludge prior to anaerobic digestion substantially increases the energy recovery -- the two types of wastes have complementary attributes, so they generate more energy combined than separately. Composting food waste is much more expensive than composting yard waste, and this would reduce or eliminate what we have to pay external vendors to haul and compost our food waste.

Some yard waste might be used to "bulk up" the food and sewage sludge before anaerobic digestion. The remainder of the yard waste could be mixed with clean foodwaste and digested separately to recover energy. The resulting "digestate" could then be composted into a home-garden quality soil amendment.

I support the initiative to undedicate a small amount of the current landfill land to give our regional facility the flexibility to build an anerobic digestion facility. Cedric's posts show how the preliminary feasibility study indicates that such a facility will save us considerable money over a 20 year period. If that holds, then this would definitely be a desirable project.

Posted by Typical Dictatorship, a resident of Midtown
on Mar 6, 2011 at 2:38 pm

of people with too much time on their hands who want to spend a bunch of other people's money on a project that is likely to be fraught with problems. Palo Alto doesn't need this. Go try your utopian experiments elsewhere

Posted by Craig Laughton, a resident of College Terrace
on Mar 6, 2011 at 3:16 pm

There is a lot of avoidance going on in the above posts. Anaerobic digestion (AD) is NOT the best answer, not even a reasonable answer. Why is this still being considered, in a serious way?

The best answer, considering the parameters, is plasma arc. Plasma arc actually SOLVES many of the issues, including toxics isolation, volume reduction, greenhouse gases (relative to AD) and cost reductions. Plasma arc requires considerably LESS industrial footprint, compared to AD.

When will the AD true believers finally wake up to reality?

Plasma arc is a solution, not just a kick-the-can-down-the-road, make believe 'solution'. The Salinas Valley Solid Waste Authority looked at a variety of options, and decided that plasma arc was a real solution, while AD was not (without a major state subsidy, which was denied).

Why are we still considering outmoded, and expensive ideas?

Palo Alto should be a progressinve, forward-thinking community, and part of the future, not part of of a reactionary past. AD is a non-solution, and it is part of a deal that sends our waste products into the backyard of the relatively poor and people of color. Is this what we are REALLY about?

Isn't it time that we actually deal with our own 'trash' issues, like enlightended adults?

Posted by Craig, Meet Capitalism, a resident of Midtown
on Mar 6, 2011 at 3:41 pm

I don't want to pay for any of your speculative "solutions" with my hard-earned money. If someone wants to build something under contract, with a guarantee that it will save Palo Alto money over hauling-- where THEY take on the price risk, then great. Otherwise, paying garbage companies to haul waste is not a crime or something to feel guilty about.

Posted by anon, a resident of Another Palo Alto neighborhood
on Mar 6, 2011 at 5:00 pm

If the 10 acres of currently defined future parkland is undedicated, what happens to it if the project turns out to not make financial sense and is not approved. Would there be any restrictions on what could be done with that land or would there be a possibility of a hotel/office building complex/etc being built there?

Posted by Craig Laughton, a resident of College Terrace
on Mar 6, 2011 at 5:08 pm

Craig (capitalist),

"I don't want to pay for any of your speculative "solutions" with my hard-earned money. If someone wants to build something under contract, with a guarantee that it will save Palo Alto money over hauling-- where THEY take on the price risk, then great."

I completely agree! That is one of the several reasons why I don't think that AD is a solution. Plasma arc would need to stand on its own, without subsidy, as it is doing in the Salinas Valley, and elsewhere around the world. No tricks, no speculation, no subsidies...just performance, under contract.

AD is the real "trick" in this equation. AD requires subsidies, inefficiencies, greater industrial footprint...yet it only partially sovles any current problems, and it is highly unlikely that any AD company would agree to a subsidy-free contract. AD ends up exporting a lot of our own, self-generated, problems. Those problems get dumped on others...is that really us, in Palo Alto?

I want a real solution, not a phantom solution. That is real capitlalism, and I am a believer in capitalism. Are you, Craig ("capitalist")? BTW, I am completely comfortable using my full name and address. I live at 2321 Harvard St., in Palo Alto. May I suggest that you, and some others in this debate, use your real names? That would add some gravitas to your arguments. I am willing to stand up to the debate, because I can defend my arguments, with real-world facts.

I think science and technology and engineering offer real solutions to real problems.

Posted by Garbage IDEAS, a resident of Community Center
on Mar 6, 2011 at 10:37 pm

I have a new experiment to offer (better than plasma arc and more):
Lets make pan cakes out of the sludge, fry them and use it as low calorie diet.
Enough of this garbage. We dont need to solve this problem we will copy what other cities around us are doing. Palo Alto need not "go it alone".

Posted by Bob, a resident of Barron Park
on Oct 14, 2011 at 1:19 am

Craig: "AD is a non-solution, and it is part of a deal that sends our waste products into the backyard of the relatively poor and people of color."